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Large area Germanium Tin nanometer optical film coatings on highly flexible aluminum substrates

View Article: PubMed Central - PubMed

ABSTRACT

Germanium Tin (GeSn) films have drawn great interest for their visible and near-infrared optoelectronics properties. Here, we demonstrate large area Germanium Tin nanometer thin films grown on highly flexible aluminum foil substrates using low-temperature molecular beam epitaxy (MBE). Ultra-thin (10–180 nm) GeSn film-coated aluminum foils display a wide color spectra with an absorption wavelength ranging from 400–1800 nm due to its strong optical interference effect. The light absorption ratio for nanometer GeSn/Al foil heterostructures can be enhanced up to 85%. Moreover, the structure exhibits excellent mechanical flexibility and can be cut or bent into many shapes, which facilitates a wide range of flexible photonics. Micro-Raman studies reveal a large tensile strain change with GeSn thickness, which arises from lattice deformations. In particular, nano-sized Sn-enriched GeSn dots appeared in the GeSn coatings that had a thickness greater than 50 nm, which induced an additional light absorption depression around 13.89 μm wavelength. These findings are promising for practical flexible photovoltaic and photodetector applications ranging from the visible to near-infrared wavelengths.

No MeSH data available.


(a) Micro-Raman spectroscopy measurement for the nanometer GeSn thin films coating on Al foil with different t. (b) Enlarged Ge-Ge peak shift as function of GeSn thickness.
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f2: (a) Micro-Raman spectroscopy measurement for the nanometer GeSn thin films coating on Al foil with different t. (b) Enlarged Ge-Ge peak shift as function of GeSn thickness.

Mentions: Room temperature micro-Raman spectroscopy for GeSn nanometer thin film coatings on Al foil with different thicknesses are shown in Fig. 2(a). A HeNe 532 nm laser was used as an excitation source. The exact wavenumber position of the peaks reflects the influence of chemical composition and strain. All Raman spectra present a strong Ge-Ge 1st peak located at ~292 cm−1. While, Ge-Ge 2nd peak locates at ~544 cm−1. It compares well with previous results of GeSn epitaxial growth on Si and SiO2192021. The typical Ge-Sn peak always displays at lower wavenumber 250-260 cm−1. Actually, the shoulder on the left side of the Ge-Ge 1st peak is due to the Ge-Sn peak at ~285 cm−1 22. The typical Ge-Al peak is at ~370 cm−1 23, however, in this work the Al implanted GeSn can be excluded from the Raman spectra.


Large area Germanium Tin nanometer optical film coatings on highly flexible aluminum substrates
(a) Micro-Raman spectroscopy measurement for the nanometer GeSn thin films coating on Al foil with different t. (b) Enlarged Ge-Ge peak shift as function of GeSn thickness.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036029&req=5

f2: (a) Micro-Raman spectroscopy measurement for the nanometer GeSn thin films coating on Al foil with different t. (b) Enlarged Ge-Ge peak shift as function of GeSn thickness.
Mentions: Room temperature micro-Raman spectroscopy for GeSn nanometer thin film coatings on Al foil with different thicknesses are shown in Fig. 2(a). A HeNe 532 nm laser was used as an excitation source. The exact wavenumber position of the peaks reflects the influence of chemical composition and strain. All Raman spectra present a strong Ge-Ge 1st peak located at ~292 cm−1. While, Ge-Ge 2nd peak locates at ~544 cm−1. It compares well with previous results of GeSn epitaxial growth on Si and SiO2192021. The typical Ge-Sn peak always displays at lower wavenumber 250-260 cm−1. Actually, the shoulder on the left side of the Ge-Ge 1st peak is due to the Ge-Sn peak at ~285 cm−1 22. The typical Ge-Al peak is at ~370 cm−1 23, however, in this work the Al implanted GeSn can be excluded from the Raman spectra.

View Article: PubMed Central - PubMed

ABSTRACT

Germanium Tin (GeSn) films have drawn great interest for their visible and near-infrared optoelectronics properties. Here, we demonstrate large area Germanium Tin nanometer thin films grown on highly flexible aluminum foil substrates using low-temperature molecular beam epitaxy (MBE). Ultra-thin (10–180 nm) GeSn film-coated aluminum foils display a wide color spectra with an absorption wavelength ranging from 400–1800 nm due to its strong optical interference effect. The light absorption ratio for nanometer GeSn/Al foil heterostructures can be enhanced up to 85%. Moreover, the structure exhibits excellent mechanical flexibility and can be cut or bent into many shapes, which facilitates a wide range of flexible photonics. Micro-Raman studies reveal a large tensile strain change with GeSn thickness, which arises from lattice deformations. In particular, nano-sized Sn-enriched GeSn dots appeared in the GeSn coatings that had a thickness greater than 50 nm, which induced an additional light absorption depression around 13.89 μm wavelength. These findings are promising for practical flexible photovoltaic and photodetector applications ranging from the visible to near-infrared wavelengths.

No MeSH data available.